Eggs live for decades without losing the ability to fuse with sperm. However, the mechanisms that allow this or how this situation fails are unknown.

Sperm fertilizing the egg. (Photo. Freepik)

every year the infertility in our country. A reality that affects 15 and 17% of the Spanish population, 800,000 couples with reproductive problems according to data from the Spanish Fertility Society (SEF). It is estimated that 15% of men are infertile for various reasons, such as genetic diseases that prevent them from producing sperm (azoospermia) or produce less (oligospermia). They are the cause of 40% of a couple’s fertility problems. Women can also cause or contribute to the couple’s infertility, but their situation is much less known.

So far, there is evidence that there are several factors involved in the fertility problems in women. Pathologies such as untreated celiac disease, diabetes, cancer, environmental agents or emotional problems are some of the situations that can lead to female disability. But the reality is that currently the causes of one in four cases are unknown. “There is still a certain lack of knowledge about the functioning of the female reproductive system or the causes of infertility”, explains o Dr. Rita Vassena, member of the Board of SEF and specialist in this area of ​​investigation.

“When I was first confronted with what had been written about egg biology, I realized how little we knew and started looking into it,” says Dr. Boke.

It is known that, like neurons, Eggs are long-lived cells. These start to deteriorate after 20-30 years, leading to genetic errors or impossibility of pregnancy. Why do these errors occur? With access to motherhood becoming increasingly delayed in populations such as Spain or the United States, answering this question is essential.

In this context, a research group from Center for Genomic Regulation (CRG) driven by doctor Elvan Böke is working to identify the cellular mechanisms involved in reproduction and to unravel the mysteries of human eggs. “When I first came across what he had written about egg biology, I realized how little we knew and started looking into it,” points out Dr. Böke to this medium.


In recent years, much progress has been made in the genetic factors of infertility. And, in this sense, much progress has been made in the reproductive function of eggs. Over the years, they lose number and quality, making genetic errors more likely as the eggs mature (an example of the increased risk of Down syndrome as women are older). “The more time passes, the harder it is to get pregnant and the easier it is to lose it,” Dr. Vassena.

Cells use alternative metabolic pathways to generate energy never before seen in other types of animal cells

In this context, it is known that there are mechanisms that affect the ability of eggs to produce adequate genetic maturation. The eggs, which are the same from birth to gestation, whether at 30 or 40 years old. And despite their age, babies born at term do not reflect primordial cell aging.

The research group led by Dr. Elvan Böke investigated the health protection mechanisms of the egg. As they showed in the magazine ‘Nature’ that the cells use alternative metabolic pathways to generate energy never before seen in other types of animal cells, a pathway that allows eggs to wait for years without losing quality.

A first discovery that allows the authors to continue investigating the Strategies used by oocytes prevent aging “It is how these strategies fail with advancing age of women,” says Dr. Boke. “Finding out how eggs age and the molecular mechanisms involved is essential for research on female infertility and to mitigate, in some way, its effects in a society whose women increasingly access motherhood later in life”, concludes Dr. Vassena.

Because health we all need…